CAUGHT! – by Silent Sounds (May, 1954)

How had the burglar been detected ? No one saw him enter. There was 110 watchman. And no sign of an alarm system.

No obvious sign, that is. But there was a system — the Alertronic Burglar Alarm.
This unusual protective device operates by sending out 19,200 cycle-a-second sound waves, too high for human ears to hear. The slightest movement of an intruder disturbs these waves of silent sound and activates the alarm. It’s so sensitive that even the motion of heated air rising from a fire sets it off.

What produces the vibrations? Two slender nickel rods—and a principle of physics called magnetostriction (the peculiar way they change size in a changing magnetic field).

Putting magnetostriction to work in this ultrasonic burglar alarm — the first ever to be approved by The Underwriters’ Laboratories — wasn’t an overnight job. It was twelve years ago that the inventor made his first experiments.

The search for a material with necessary magnetostrictive properties ended when he came to Inco — for nickel proved to be the material he was seeking.

And, as it turned out, he got more than a metal from Inco . . .

In the years that have passed, he has found Inco always ready to help in supplying information on the physical and mechanical properties of Inco Nickel Alloys and other metals … on the technical aspects of magnetostriction … and on questions involving metal fabrication.

This same type of friendly cooperation, of course, is available to you for the asking. Let’s get together on your problem.